In recent years, avionics engineers have endeavored to enhance the performance of Liquid Crystal Displays. Of the many design and environmental parameters found to affect LCD performance, temperature ranks among those with the greatest impact. Current designs attempt to regulate and/or compensate for temperature fluctuation by monitoring the temperature of the display surface using temperature sensors and adjusting drive parameters and heater controls.
While this approach improves performance over designs which neglect temperature dependence, it has several shortcomings. For example,
1. The temperature reading is taken on the outside of the grass. Consequently, there may be a significant difference between that measured temperature and the temperature of the liquid crystal material. PA1 2. The sensor temperature rise/fall lags or leads the temperature of the liquid crystal material due to proximity. This injects a risk of damaging the display by continuing to heat it beyond safe limits. PA1 3. Corrections to the drive parameters are based on the actual response of the liquid-crystal material which does not vary linearly with temperature. Therefore, circuitry that attempts to use temperature readings to control the heater and drive parameters can be very complicated or wildly inaccurate.
Consequently, there exists a need for an improved method for monitoring the temperature-dependent characteristics of an LCD.